Under warm ambient conditions, Drosophila melanogaster suppresses nighttime activity via the neuropeptide pigment dispersing factor

• Published in: Genes, brain and behavior brain and behavior, 2022-04, Vol.21 (4), p.e12802-n/a
• Main Authors: Iyengar, Aishwariya Srikala, Kulkarni, Rutvij, Sheeba, Vasu
• Format: Article
• Language: English
• Subjects: activity suppression; Animals; circadian clock; Circadian rhythm; Circadian Rhythm - genetics; Circadian rhythms; Drosophila melanogaster; Drosophila melanogaster - genetics; Drosophila Proteins - genetics; Locomotor activity; midnight activity; Motor Activity - genetics; Neuropeptides; Neuropeptides - genetics; Original; Pacemakers; pigment dispersing factor; ventral‐lateral neurons; warm temperature
• ISSN: 1601-1848; 1601-183X
• DOI: 10.1111/gbb.12802

Rhythmic locomotor behaviour of flies is controlled by an endogenous time‐keeping mechanism, the circadian clock, and is influenced by environmental temperatures. Flies inherently prefer cool temperatures around 25°C, and under such conditions, time their locomotor activity to occur at dawn and dusk. Under relatively warmer conditions such as 30°C, flies shift their activity into the night, advancing their morning activity bout into the early morning, before lights‐ON, and delaying their evening activity into early night. The molecular basis for such temperature‐dependent behavioural modulation has been associated with core circadian clock genes, but the neuronal basis is not yet clear. Under relatively cool temperatures such as 25°C, the role of the circadian pacemaker ventrolateral neurons (LNvs), along with a major neuropeptide secreted by them, pigment dispersing factor (PDF), has been showed in regulating various aspects of locomotor activity rhythms. However, the role of the LNvs and PDF in warm temperature‐mediated behavioural modulation has not been explored. We show here that flies lacking proper PDF signalling or the LNvs altogether, cannot suppress their locomotor activity resulting in loss of sleep during the middle of the night, and thus describe a novel role for PDF signalling and the LNvs in behavioural modulation under warm ambient conditions. In a rapidly warming world, such behavioural plasticity may enable organisms to respond to harsh temperatures in the environment. The ventrolateral neurons and PDF in circadian pacemakers suppress nocturnal activity of flies under warm temperature. Under relatively warm conditions, flies shift their activity into the night, advancing their morning activity bout into early morning, and delaying their evening activity into early night. We show here that flies lacking proper PDF signalling or lacking the LNvs altogether, cannot suppress their locomotor activity during the middle of the night, resulting in loss of sleep, thereby uncovering a novel role for PDF signalling and the LNvs in behavioural modulation in the context of warm ambient conditions.